Magnetically guided catheter with concentric needle port

ABSTRACT

A catheter adapted for ablation, mapping, injection, and directional control by an external magnetic system has a catheter body, an intermediate section, and a tip section having a tip electrode configured with an omnidirectional distal end and a concentric needle port. The tip electrode houses a magnetic device and a position sensor arranged in an integrated configuration, wherein the configuration facilitates a path in the tip section for a component, including an injection needle, to extend through the tip section for extension and retraction with reduced stress and friction. The integrated configuration is an efficient use of space in the tip electrode that allows the tip section to carry both the position sensor for determining location and orientation of the tip section and the necessary volume of magnetic or magnetizable material to accomplish magnetic navigation. The catheter also includes a very soft and flexible intermediate section and an even softer and more flexible distal transitional section carrying additional magnetic members to facilitate remote magnetic navigation.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application is a divisional of U.S. patent application Ser. No.12/125,903 filed May 22, 2008, which claims the priority of U.S.Provisional Patent Application No. 60/939,649, filed May 23, 2007, theentire contents of both of which are incorporated herein by reference.

FIELD OF INVENTION

The present invention relates to electrophysiology catheters, and inparticular to magnetic navigation and injection catheters.

BACKGROUND

Electrode catheters have been in common use in medical practice for manyyears. They have been used to stimulate and map electrical activity inthe heart and to ablate sites of aberrant electrical activity. Morerecently, therapeutic and diagnostic agents have been delivered into theheart, including the heart wall, through a percutaneous transluminalapproach with the use of catheters. In particular, catheters with aneedle have been used for injection directly into the myocardium for avariety of treatments, including myocardial revascularization. Forexample, U.S. Pat. No. 6,309,370 entitled Intracardiac Drug Delivery,the entire disclosure of which is hereby incorporated by reference, isdirected methods and apparatuses to provide accurate minimally-invasivemethods and apparatus for intracardiac administration of drugs to themyocardium.

In use, the electrode catheter is inserted into a major vein or artery,e.g., femoral. artery, and then guided into the chamber of the heart ofconcern. Navigation of the catheter has been accomplished largely withthe use of fluoroscopy which poses radiation concerns for both thepatient and the treating physician. Moreover, within the heart, theability to control the exact position and orientation of the cathetertip is critical and largely determines how useful the catheter is.Electromagnetic position sensors have been in use in catheter tips formany years. While these sensors provide useful data to determinelocation and position of the catheter, they can be relatively large andconsequently tend to occupy a significant amount of space in thecatheter tip.

In recent years, magnetically navigable and controllable catheters havebeen used. These catheters have allowed more aspects of ablation andmapping procedures to be automated for improved accuracy and efficiency.They also provide the benefit of lowering radiation exposure at leastfor the treating physicians by enabling catheter control from a remotelocation away from the patient. However, because space in the cathetertip is at a premium, the integration of ablation, mapping and injectioncapabilities with magnetic navigation in a catheter tip has beenchallenging. While such catheters exist, the catheter tips tend to lacksufficient volume of magnetic material for adequate magnetic navigationand control and their needle ports have been generally eccentric oroff-axis. Moreover, the injection needle is generally made of arelatively stiff material that allows the translation of force to enablethe extension. However, added stiffness tends to make it more difficultto adequately deflect the catheter without increasing magnetic volume.The action of injection requires the tip of the catheter to remain incontact with tissue surface. Insufficient magnetic “adhesion” forcewould limit the ability of the needle to penetrate tissue.

Accordingly, it is desirable to provide a magnetically navigable andcontrollable catheter whose tip section carries adequate elements forablation, mapping and injection. Particularly desirable is a catheterhaving a tip section with an omnidirectional tip electrode and aconcentric needle port for greater tip angulation while housing aposition sensor and a sufficient volume of magnetic or magnetizablematerial to enable suitable magnetic response to an external magneticsurgery system.

SUMMARY OF THE INVENTION

The present invention is directed to an electrophysiology catheter thatis adapted for ablation, mapping, injection, and directional control byan external magnetic system, including a magnetic surgery system (MSS).In one embodiment, the catheter has a catheter body, an intermediatesection, and a tip section having a tip electrode configured with anomnidirectional distal end and a concentric needle port. Theomnidirectional distal end of the tip electrode improves maneuverabilityand angulation. A dome configuration enables a wide range of tissuecontact angles. The concentric needle port provides optimal tissueinjection success.

In a more detailed embodiment, the tip electrode houses a magneticdevice and a position sensor arranged in an integrated configuration,wherein the configuration facilitates a path in the tip section for acomponent, including an injection needle, to extend through the tipsection for extension and retraction with reduced stress and friction.The integrated configuration is an efficient use of space in the tipelectrode that allows the tip section to carry both the position sensorfor determining location and orientation of the tip section and thenecessary volume of magnetic or magnetizable material for magneticnavigation. The path defined by the integrated magnetic device andposition sensor through the tip section can be generally linear ornonlinear depending on the structure design of the magnetic device andposition sensor. For the injection needle, the path connects with theconcentric needle port whether the path is on axis or off axis with thetip electrode. The catheter also includes a very soft and flexibleintermediate section and an even softer and more flexible distaltransitional section carrying additional magnetic members to facilitateremote magnetic navigation.

The present invention contemplates the magnetic device having either amonolithic structure or a modular structure comprising multiple pieces.For an integrated arrangement, one or both of the magnetic device andthe position sensor are hollow so that they can assume a surroundingrelationship, including a circumferential relationship, to minimize thespace they occupy in the tip electrode without blocking components fromreaching the tip electrode. Moreover, a member of the magnetic devicecan be configured as a spacer to situate the sensor a predetermineddistance from the distal end of the tip electrode so that systems anddevices processing signals from the sensors based on a known distancebetween the sensor and the distal tip of the tip electrode can reliablydetect the position of the sensor.

In accordance with a feature of the present invention, the intermediatesection or at least a portion thereof is especially floppy and soft fora “soft touch.” To that end, the intermediate section is constructed ofa low durometer tubing reinforced with a spring coil so that stiffnessof the intermediate section stems primarily from the components passingtherethrough, including the injection needle and its overtubing. Asofter and more flexible distal transitional section carrying additionalmagnets has no structures beyond connective tubings, the magneticssecured therebetween, and heat shrinking protective sleeves for themagnets, such that stiffness stems primarily from the componentsextending therethrough.

In more detailed embodiments, the catheter carries a ring electrode forbipolar electrode configuration on the tip section. While the catheterin an embodiment includes a needle injection control handle, theextension and retraction and even actuation of fluid flow through theneedle can be automated such as by means of an automated injectiondevice and system such as disclosed in U.S. Patent Application EntitledAUTOMATED INJECTION CATHETER DEVICE AND SYSTEM, naming inventorsChristopher J. Birchard, et al., Ser. No. 12/125,893, filed on even dateherewith, the entire disclosure of which is hereby incorporated byreference.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features and advantages of the present invention will bebetter understood by reference to the following detailed descriptionwhen considered in conjunction with the accompanying drawings. It isunderstood that selected structures and features have not been shown incertain drawings so as to provide better viewing of the remainingstructures and features.

FIG. 1 is a side view of an embodiment of the catheter of the presentinvention.

FIG. 2 is a side cross-sectional view of an embodiment of a catheteraccording to the invention, including a junction between a catheter bodyand an intermediate section.

FIG. 3 is a side cross-sectional view of an embodiment of a connectionhousing according to the invention.

FIG. 4 is a side cross-sectional view of an embodiment of a needlecontrol handle according to the invention, in a resting configurationwhere the injection needle is in the retracted position.

FIG. 4 a is a side cross-sectional view of an embodiment of a needlecontrol handle according to the invention, in an actuated configurationwhere the injection needle is in the extended position.

FIG. 5 is a perspective view of an embodiment of a tip section accordingto the invention.

FIG. 6 is an exploded view of the tip section of FIG. 5.

FIG. 6A is a longitudinal cross-sectional view of another embodiment ofa tip electrode.

FIG. 7 is a top plan view of the tip section of FIG. 5.

FIG. 7 a is a cross-sectional view of the tip electrode and distalmagnetic member of FIG. 5, taken along a first diameter.

FIG. 7 b is a cross-sectional view of the tip electrode at differentangles of tissue contact.

FIG. 8 is a cross sectional view of the tip section of FIG. 5, takenalong a second diameter.

FIG. 8 a is a longitudinal cross sectional view of the tip section ofFIG. 8, taken along line a-a.

FIG. 8 b is a longitudinal cross sectional view of the tip section ofFIG. 8, taken along line b-b.

FIG. 8 c is a longitudinal cross sectional view of the tip section ofFIG. 8, taken along line c-c.

FIG. 8 d is a longitudinal cross sectional view of the tip section ofFIG. 8, taken along line d-d.

FIG. 8 e is a longitudinal cross sectional view of the tip section ofFIG. 8, taken along line e-e.

FIG. 8 f is a longitudinal cross sectional view of the tip section ofFIG. 8, taken along line f-f.

FIG. 8 g is a longitudinal cross sectional view of the tip section ofFIG. 8, taken along line g-g.

FIG. 9 is a cross sectional view of an embodiment of a catheter,including a junction between a distal transitional section and theintermediate section.

FIG. 10 is a perspective view of another embodiment of a tip sectionaccording to the invention.

FIG. 11 is a perspective view of an embodiment of the magnetic device ofthe tip section of FIG. 10.

FIG. 11 a is a perspective view of another embodiment of the magneticdevice.

FIG. 12 is an exploded perspective view of an embodiment of a hollowposition sensor.

FIG. 13 is a cross-sectional view of the tip section of FIG. 10.

FIG. 13 a is a longitudinal cross sectional view of the tip section ofFIG. 13, taken along line a-a.

FIG. 13 b is a longitudinal cross sectional view of the tip section ofFIG. 13, taken along line b-b.

FIG. 13 c is a longitudinal cross sectional view of the tip section ofFIG. 13, taken along line c-c.

FIG. 13 d is a longitudinal cross sectional view of the tip section ofFIG. 13, taken along line d-d.

FIG. 13 e is a longitudinal cross sectional view of the tip section ofFIG. 13, taken along line e-e.

FIG. 13 f is a longitudinal cross sectional view of the tip section ofFIG. 13, taken along line f-f.

DETAILED DESCRIPTION OF THE INVENTION

As shown in FIGS. 1-9, catheter 10 of the present invention comprises anelongated catheter body 12 having proximal and distal ends, a very softand flexible intermediate section 14 at the distal end of the catheterbody 12, a magnetically-maneuverable tip section 36 through which aninjection needle 46 can be extended and retracted, a connection housing16 at the proximal end of the catheter body and a needle control handle17 proximal of the housing 16, by which a user can manipulate needleextension and retraction. In accordance with a feature of the invention,the tip section includes a tip electrode 37 for ablation and mapping, anelectromagnetic position sensor 34 to provide location and orientationdata, and a magnetic device 38 to facilitate magnetic navigation andcontrol.

With reference to FIGS. 1 and 2, the catheter body 12 comprises anelongated tubular construction having a single, axial or central lumen18. The catheter body 12 is flexible, i.e., bendable, but substantiallynon-compressible along its length. The catheter body 12 can be of anysuitable construction and made of any suitable material. A constructioncomprises an outer wall 22 made of an extruded plastic. The outer wall22 may comprise an imbedded braided mesh of stainless steel or the liketo increase torsional stiffness of the catheter body 12 so that thecatheter body 12, the intermediate section 14 and the tip section 36 ofthe catheter 10 all rotate in a corresponding manner.

Extending through the single lumen 18 of the catheter body 12 arecomponents, for example, an injection needle 46, lead wires 40 toenergize electrodes and thermocouple wires 41 to sense tip and/or tissuetemperature. A single lumen catheter body can be preferred over amulti-lumen body because it has been found that the single lumen bodypermits better tip control when rotating the catheter. The single lumenpermits the aforementioned components to float freely within thecatheter body and minimize undesirable performance characteristics suchas unintended rotation, twisting or flipping of the catheter body.

The outer diameter of the catheter body 12 is not critical, but ispreferably no more than about 8 french, more preferably 7 french.Likewise the thickness of the outer wall 22 is not critical, but is thinenough so that the central lumen 18 can accommodate the aforementionedcomponents. The braided outer wall 22 provides improved torsionalstability while at the same time minimizing the wall thickness of thecatheter, thus maximizing the diameter of the central lumen 18. Thecatheter body 12 may have an outer wall 22 with an outer diameter offrom about 0.090 inch to about 0.104 inch and an inner diameter of fromabout 0.061 inch to about 0.075 inch. In one embodiment, the catheterbody 12 is constructed of braided PEBAX tubing.

Referring also to FIG. 2, the intermediate section 14 distal of thecatheter body 12 comprises a shorter section of tubing 19 having asingle lumen. The tubing 19 is made of a suitable non-toxic materialthat is considerably softer and more flexible than the catheter body 12.A suitable material for the tubing 19 is PEBAX tubing with a low tomedium durometer plastic, for example, within the ranges of about 25D to55D, preferably of about 30D to 40D, more preferably of about 35D. Theouter diameter of the intermediate section 14, like that of the catheterbody 12, is preferably no greater than about 8 french, more preferablyless than 7 french. (0.092 inch). The length of the tubing 19 is withinthe ranges of about 1.5 in. to 8.0 in., preferably of about 2.0 in. to6.0 in., more preferably of about 4.0 in to 5.0 in. Notably, stiffnessof the intermediate section 14 is provided primarily by the componentsextending through it such as the lead wires, safety wire,electromagnetic position sensor cable, and injection needle, althoughthere is a spring coil 27 extending within the tubing 19. It is afeature of the present invention that the intermediate section has a“soft touch” in that it is sufficiently soft, and flexible and allowsthe tip section to be adequately maneuvered by the MSS notwithstandingthe presence of the aforementioned components, including a nitinolinjection needle and its overtubing.

The catheter body 12 may be attached to the intermediate section 14 bybutt fusing the distal end of the tubing of the catheter body and theproximal end of the tubing 12 using a combination of heat, pressure(along the longitudinal axis). A PET shrink sleeving is used temporarilyto control the flow of the PEBAX and removed after the ends have fused.The spring coil 27 extends proximally into the catheter body 12 a shortdistance (for example, about 3.0 mm) to ensure adequate anchorage.

With reference to FIG. 3, distal of the catheter body 12 is theconnection housing 16 for various components, including the lead wires40, thermocouple wires 41 and 45, the injection needle 46 andelectromagnetic sensor cable 42, all of which extend into the housingthrough the catheter body by means of a shrink sleeve 28. The lead wires40 extend out through housing 16, and terminate at their proximal end inan input jack (not shown) that may be plugged into an appropriate signalprocessing unit (not shown) and source of RF energy (not shown). Theelectromagnetic sensor cable 42 connects to a circuit board 64 in thehousing 16. The circuit board 64 amplifies the signal received from theelectromagnetic sensor 34 and transmits it to a computer in a formunderstandable by the computer. Also, because the catheter is designedfor single use only, the circuit board contains an EPROM chip whichshuts down the circuit board after the catheter has been used. Thisprevents the catheter, or at least the electromagnetic sensor 34, frombeing used twice. The connection housing 16 is illustrated as agenerally cylindrical structure, but it is understood by one of ordinaryskill in the art that the housing may assume any shape or configuration,including that of a conventional catheter control handle, to facilitateits handling, use and or storage by a user.

The wires 41 and 45 extend out through the housing 16 and to a connector(not shown) connectable to a temperature monitor (not shown). Theinjection needle 46 and protective tube 47 extend through one or moreguide tube 66, preferably made of polyurethane, and are affordedlongitudinal movement and protection against buckling, sharp bends inthe housing and contact with the circuit board, as they emerge from theproximal end of the housing toward the needle control handle 17.

Extension and retraction of the injection needle 46 in the tip electrode37 is accomplished by the needle control handle 17. In the illustratedembodiment of FIGS. 4 and 4 a, the needle control handle 17 comprises agenerally cylindrical outer body 80 having proximal and distal ends, apiston chamber 82 extending a part of the way therethrough, and a needlepassage 83 extending a part of the way therethrough. The piston chamber82 extends from the proximal end of the handle part way into the body80, but does not extend out the distal end of the body. The needlepassage 83, which has a diameter less than that of the piston chamber82, extends from the proximal end of the piston chamber to the proximalend of the outer body 80.

A piston 84, having proximal and distal ends, is slidably mounted withinthe piston chamber 82. A luer connector 86 is mounted in the proximalend of the outer body. The piston 84 has an axial passage 85 throughwhich the injection needle 46 extends, as described in more detailbelow. A compression spring 88 is mounted within the piston chamber 82between the distal end of the piston 84 and the outer body 80.

The proximal end of the injection needle 46 is mounted to the luerconnector 86 by means of a first rigid tube 90, preferably made ofstainless steel, which has a proximal end fitted into the luerconnector. This arrangement fixedly attaches the injection needle 46 tothe piston 84 so that it moves longitudinally with the piston. The firstrigid tube 90 is also fixedly attached to the piston 84 and moveslongitudinally with the piston. The injection needle 46 and first rigidtube 90 extend through the axial passage 85 of the piston 84. Within theaxial passage 85, a second rigid tube 91, preferably made of stainlesssteel, has a proximal end mounted coaxially within the distal end of thefirst rigid tube 90. The proximal end of the second rigid tube 91 ismounted within the protective tube 47, which has its proximal end insidethe axial passage 85, and the distal end of the second rigid tube isattached, directly or indirectly, to the outer body 80. The guide tube66, through which the protective tube 47 and injection needle 46 extend,as discussed above, is fixedly attached to the outer body 80 by means ofa shrink sleeve 92, as is generally known in the art.

In use, force is applied to the piston 84 to cause distal movement ofthe piston relative to the body 80, which compresses the compressionspring 88. This movement causes the injection needle 46 tocorrespondingly move distally relative to the body 80, guide tube 66,protective tube 47 and catheter body 12, so that the distal end of theinjection needle extends outside the distal end of the tip electrode 37.When the force is removed from the piston, the compression spring 88pushes the piston 84 proximally to its original position, thus causingthe distal end of the injection needle 46 to retract back into the tipelectrode 37. Upon distal movement of the piston 84, the first rigidtube 91 moves distally over the second rigid tube 91 to prevent theinjection needle 46 from buckling within the axial passage 85.

The piston 84 further comprises a longitudinal slot 100 extending alonga portion of its outer edge. A set screw 102 extends through the outerbody 80 and into the longitudinal slot 100. This design limits thedistance that the piston can be slid proximally out of the pistonchamber 82. When the distal end of the injection needle 46 is in theretracted position, the set screw 102 can be set at or near the distalend of the longitudinal slot 100.

The proximal end of the piston 84 has a threaded outer surface 104. Acircular thumb control 106 is mounted on the proximal end of the piston.The thumb control 106 has a threaded inner surface 108 that interactswith the threaded outer surface 104 of the piston. The thumb control 106acts as a stop, limiting the distance that the piston 84 can be pushedinto the piston chamber 82, and thus the distance that the injectionneedle 46 can be extended out the distal end of the catheter. Thethreaded surfaces of the thumb control 106 and piston 84 allow the thumbcontrol to be moved closer or farther from the proximal end of the outerbody 80 so that the extension distance of the injection needle can becontrolled by the physician. A tension screw 110 is provided in thethumb control 106 to control the tension between the thumb control andpiston 84. As would be recognized by one skilled in the art, the thumbcontrol 106 can be replaced by any other mechanism that can act as astop for limiting the distance that the piston 84 extends into thepiston chamber 82, and it is not necessary, although it is preferred,that the stop be adjustable relative to the piston. Suitable needlecontrol handles are described in U.S. Pat. Nos. 6,540,725 and 6,575,931,and co-pending application entitled EXTENSION CONTROL HANDLE WITHADJUSTABLE LOCKING MECHANISM, naming inventor Christopher Birchard,filed on even date herewith, Ser. No. 12/125,890, the entire disclosureof which is hereby incorporated by reference.

Distal end of the intermediate section 14 is the tip section 36 thatincludes the tip electrode 37 adapted for ablation and needle injection,an embodiment of which is illustrated in FIG. 5. Also provided is a ringelectrode 54 proximal of the tip electrode and separated therefrom by ashort segment of insulating tubing 57. Included in the tip section 36are the electromagnetic position sensor 34 and the magnetic device 38housed together in a heat shrink protective tubing 39 (shown partiallybroken away) extending between the ring electrode and the proximal endof the tip section.

As understood by one of ordinary skill in the art, the electromagneticposition sensor 34 enables determination of position and orientationcoordinates (for example, x, y, z, pitch, roll, yaw) of the tip section.Suitable electromagnetic sensors for use in connection with the presentinvention are described, for example, in U.S. Pat. Nos. 4,391,199 and6,201,387, the disclosures of which are hereby incorporated byreference. A suitable electromagnetic mapping sensor is manufactured byBiosense Webster, Inc. and marketed under the trade designation NOGA. Asuitable system for monitoring and displaying the signals received fromthe electrodes and electromagnetic sensor is marketed under the tradedesignation Biosense-NOGA system. The sensor 34 is connected to theproximal end of sensor cable 42. The electromagnetic sensor cable 42comprises multiple wires encased within a plastic sheath.

To use the electromagnetic sensor, the patient is placed in a magneticfield generated, for example, by situating under the patient a padcontaining coils for generating a magnetic field. A referenceelectromagnetic sensor (not shown) is fixed relative to the patient,e.g., taped to the patient's back, and the catheter 10 containing theelectromagnetic sensor 34 is advanced into the patient's heart. Eachsensor comprises three small coils which in the magnetic field generateweak electrical signals indicative of their position in the magneticfield. Signals generated by both the fixed reference sensor and thesensor 34 in the heart are amplified and transmitted to a computer whichanalyzes the signals and then displays the signals on a monitor. By thismethod, the precise location and orientation of the sensor 34 in thecatheter relative to the reference sensor can be ascertained andvisually displayed. The sensor 34 can also detect displacement of thecatheter that is caused by contraction of the heart muscle.

The magnetic device 38 in the tip section 36 responds to a magneticsurgery system (MSS) (not shown) that applies magnetic fields andgradients from outside the patient body so as to manipulate and directthe tip section. For optimum response to the MSS, the magnetic device(whether as monolithic piece or as a modular combination of multiplepieces) occupies a predetermined volume within the tip section so thatthe MSS can have suitable magnetic control over the tip section fordeflection and positioning against the heart wall. The ability of theMSS to hold the tip section in position is of particular importanceduring injection. Successful penetration of the needle into the heartwall requires the tip electrode to be held securely against the heartwall.

A suitable magnetic material for construction of the magnetic device 38is a Neodymium Iron Boron (NdFeB) magnet, a commercialized permanentmagnet material. NdFeB magnets are available in a number of differentgrades that span a wide range of properties and applicationrequirements. NdFeB magnets are available in sintered as well as bondedforms. NdFeB magnets can be brittle and machining operations should beperformed prior to magnetization, using diamond tools. NdFeB magnets aremanufactured in the following forms: sintered, compression bonded,injection molded and extruded. Suitable NdFeB magnets are manufacturedby Magnetic Sales & Manufacturing Inc. and marketed under the tradedesignation TOTAL MAGNETIC SOLUTIONS. Although it is understood by oneof ordinary skill in the art that the tip section can employ anysuitable magnetic or magnetizable material, a monolithic or solid designof the magnetic device 38 can allow for faster assembly of the tipsection; however, a modular design can ease manufacturing and handlingrequirements.

In accordance with a feature of the present invention, the tip electrode37 has an atraumatic omnidirectional domed outer surface 60 at itsdistal end. With reference to FIGS. 5, 7 a and 8, a distal portion ofthe tip electrode has an axially-aligned duct 62 which at its distal enddefines an injection needle port 67 that is advantageously concentricwith the distal end of the tip electrode 37. The domed distal design andthe concentric port allow for maximum contact with between the distalend and endocardial tissue 100 and for maximum penetration of the needle46 into myocardium tissue 102 for all intended angles θ of contact withnormal healthy heart wall ranging between about 10 to 90 degrees,preferably ranging between about 20 to 90 degrees, and more preferablyranging between about 45 to 90 degrees, as shown in FIG. 7 b. A proximalend 61 of the tip electrode 37 is trepanned so as to receive a distalend of the magnet device 38, as described below in further detail.

In the illustrated embodiment of FIGS. 5 and 6, the position sensor 34has a generally solid elongated cylindrical configuration and isintegrated with a modular magnetic device 38 which includes a distalmagnetic member 38 a, a mid-member 38 b and a proximal magnetic member38 c that surrounds the sensor 34 for efficient use of space within thetip section 36. Each of the magnetic members has an overall generallycylindrical configuration, and when assembled, the modular magneticdevice 38 defines a path for components to circumvent the positionsensor 34 and extend between the tip electrode 37 and the intermediatesection 14.

The mid-member 38 b has a C-shaped cross section with an outer diameterD, a cylindrical cavity 43 and an outer channel 49. The diameter andlength of the cylindrical cavity 43 are sized so that the cavity canhouse the sensor 34 and the proximal magnetic member 38 c.

The distal member 38 a has a proximal portion 63 and a neck portion 65(see FIG. 6 a). The proximal portion has an outer diameter D comparableand generally equal to the outer diameter D of the mid-member 38 b. Inthe illustrated embodiment, the neck portion 65 has a smaller diameterD′ that allows the neck 65 to be inserted into the trepanned proximalend 61 of the tip electrode. The distal member 38 a is also configuredalong its length with a notched portion 69 such that both the proximalportion 63 and the neck portion 65 have a crescent-shaped cross section(see FIGS. 8 b, 8 c and 8 d). There is also a channel 71 inclined fromthe upper edge along the length of the distal member 38 a (see FIG. 6a). The channel 71 at the distal end is deeper than the notched portion69 (see FIG. 8 b). The channel 71 at the proximal end is nearly evenwith the notched portion 69 such that the channel has diminished (FIG. 8d).

As illustrated in FIGS. 5 and 6, the sensor 34 is integrated in thecavity 43 of the mid-member 38 b, and is sandwiched between the proximalmember 38 c and the distal member 38 a. The proximal member 38 c has aninner passage 75 for the sensor cable 42 to pass through. As illustratedin FIG. 5, the distal member 38 a is in general contact with distal endsof the mid-member 38 b and the sensor 34, with its inclined channel 71and notched portion 69 longitudinally aligned with the outer channel 49of the mid-member 38 b.

The insulating tubing 57 and the ring electrode 54 are slid over theneck portion 65 before the neck portion is inserted into the trepannedproximal end 61 of the tip electrode 37. As shown in FIG. 6, the sensor34 and the magnetic device 38 form an integrated, generally cylindricalconfiguration with the sensor 34 and the mid-member 38 b in asurrounding, circumferential and coaxial relationship. Advantageously,the sensor 34 is housed in its entirety in the magnetic device 38 forefficient use of space in the tip section 36. Moreover, this integrateddesign provides a continuous and unobstructed path 111 for componentssuch as the lead wires 40, the injection needle 46, thermocouple wires41 and 45 and a tip electrode safety wire 113 to extend alongside theposition sensor 34 and the magnetic device throughout the tip section36. Depending on the component, the path 111 includes the duct 62 in thetip electrode 37, the inclined channel 71 of the distal magnetic member38 a, and the outer channel 49 of the mid-member 38 b. In theillustrated embodiment, the injection needle travels the entirety ofpath 111 in the tip section. In accordance with a feature of the presentinvention, the tip section 36 allows for the integration of thegenerally solid position sensor 34 and the magnetic device 38 whileproviding a concentric needle port 67.

In the illustrated embodiment, about half of the length of the tipelectrode 37 is trepanned to receive the neck 65 of the distal magneticmember 38 a. Notably, a length T of the distal magnetic member 38 a(FIG. 6 a) is predetermined, along with the length of the tip electrode37, so that the distal end of the sensor 34 is positioned apredetermined distance L (FIG. 5) from the distal end of the tipelectrode 37. Systems and programs that process the position andorientation signals from position sensors typically operate with a knowndistance L such that any deviation in the actual distance between thedistal end of the tip electrode and the distal end of the sensor to thedistance L can cause a misreading of the position and/or orientation.Thus, in instances where the distance L is relevant, care is given tothe proper assembly of the members 38 a, 38 b and 38 c and the sensor 34such that the distal ends of the mid-member 38 b and the sensor 34 abutthe proximal end of the distal member 38 a. Moreover, the total volumeof the magnetic devices as provided by the members 38 a, 38 b and 38 csatisfies the predetermined volume required for the tip section 36 to bemaneuvered by the MSS for suitable deflection and positioning againstthe heart wall.

The injection needle 46 extends from the needle control handle 17,through the connection housing 16, the catheter body 12, theintermediate section 14 and the tip section 36. As illustrated in FIG.3, the injection needle 46 can be formed with a beveled or unbevelededge at the distal tip of the needle. The needle 46 is coaxially mountedwithin a protective tube 47, preferably made of polyimide, which servesto prevent the needle from buckling and also serves to electricallyinsulate the needle from the tip electrode 37. The protective tube 47additionally serves to provide a fluid-tight seal surrounding theinjection needle 46. FIG. 8 depicts the injection needle 46 extendingbeyond the distal end of the tip electrode 37, as it would be positionedin order to infuse diagnostic or therapeutic fluid into the myocardium.As shown in FIG. 7 a, the distal end of the injection needle 46 iswithdrawn into the tip electrode 37 during the period of time that thecatheter is inserted through the vasculature of the body and also duringthe period of time in which the catheter is removed from the body toavoid injury. The injection needle 46 is extendable beyond the distalend of the catheter and retractable therefrom. If desired, the cathetercan include a needle stop mechanism for limiting the distance that theneedle extends beyond the distal end of the tip section 36. Such amechanism is described in U.S. Pat. No. 6,623,474, the entire disclosureof which is hereby incorporated by reference.

While the injection needle 46 can be made from one or more straightpieces of small diameter tubing having an outer diameter that allows thetubing to fit within the catheter, the injection needle of theillustrated embodiment is a single piece of nitinol tubing. In oneembodiment, the injection needle 46 has an inner diameter ranging fromabout 0.007 inch to about 0.011 inch, and an outer diameter ranging fromabout 0.012 inch to about 0.016 inch. In one embodiment, the injectionneedle 46 has a total length ranging from about 65 to about 85 inches,more preferably about 75 inches.

The tubing of the needle 46, whether plastic or metal, preferably isflexible and has straight position memory so that when it is benttemporarily, its natural tendency is to spring back to the straightposition. These properties are particularly desirable in the distalregion of the injection needle (i.e., the portion of the needle withinthe intermediate section 14) so that the needle bends and accommodatesthe deflection of the intermediate section but returns to its straightposition afterwards and pushes the intermediate section 14 back towardthe straight position to the same axis as the catheter body 12.

Additionally, the tubing of the needle 46 can be made of a biocompatiblematerial that is capable of being beveled. The material for the tubingpreferably also has a low coefficient of friction, a good surface finishfor slidability within the catheter, and the ability to be cleaned andsterilized. The good surface finish also reduces coagulate build-up onthe needle. The tubing may also have the ability to bond or fuse to anadapter for infusion.

Another suitable plastic for construction of the injection needle isPEEK (polyetheretherketone), although other suitable plastics such aspolycarbonate, polyimide, fiberglass, and composites thereof could alsobe used. Suitable metals for use in connection with the presentinvention include Nitinol and stainless steel, although Nitinol ispreferred for use at the distal region of the needle due to itsshape-memory properties. If desired, at least the distal portion of thetubing is provided with a lubricious coating, such as Teflon® orsilicone, preferably having a thickness ranging from about 0.0003 inchto about 0.002 inch. In another alternative embodiment, a biocompatiblelubricant, such as mineral oil is injected around the needle onceassembled.

In accordance with a feature of the invention, the injection needle 46is sufficiently flexible and has sufficient shape memory such that itcan be extended and retracted along the path 111 in the tip section 36.The injection needle extends through the lumen of the tubing 19 of theintermediate section 14 and the lumen of the catheter body 12 toward theconnection housing 16. Where the tubing 19 of the intermediate sectionhas a smaller diameter than the tip section 36, all components thatextend from the outer channel 49 of the mid-member 38 b smoothly conformto the change in diameter under the polyester heat shrink tubing 39 toform an atraumatic profile (see FIGS. 8 and 13). The tubing 39 extendsfrom the ring electrode 54 and to a location proximal of the magneticdevice.

To connect the tip and ring electrodes for mapping and/or RF ablationseparate lead wires 40 extend through the tip section, the intermediatesection 14, the catheter body 12, and the connection housing 16, andterminates at its proximal end in an input jack (not shown) or connector77 that may be plugged to an generator or the like (not shown). Anyportion or portions of the lead may be enclosed within protectivesheaths (not shown). In the disclosed embodiment, portions of the leadwires in the tip section 36 and immediately distal of and within thehousing 16 are enclosed in the sheath 52. The protective sheath 52 canbe made of any suitable material, preferably Teflon®.

Any conventional temperature sensing means, e.g., a thermocouple orthermistor, may be used in the catheter in applications where it isdesirable to know the tip or tissue temperature, such as duringablation. In the illustrated embodiment, a suitable temperature sensingmeans for the tip section comprises the thermocouple formed by a wirepair. One wire of the wire pair is the copper wire 41, e.g., a 40 gaugeor similar size copper wire. The other wire of the wire pair is theconstantan wire 45, which gives support and strength to the wire pair.The wires 41 and 45 extend through the lumen of the tubing 19 in theintermediate section 14. Any portion or portions of the wires 41 and 45may be enclosed in protective sheaths (not shown). In the disclosedembodiment, portions of the wires 41 and 45 in the tip section 36 andimmediately distal of and within the housing 16 are enclosed in thesheath. Alternatively, the temperature sensing means may be athermistor. A suitable thermistor for use in the present invention isModel No. AB6N2-GC14KA143T/37C sold by Thermometrics (New Jersey).

The safety wire 113 also extends into tip electrode 37 as a safetyprecaution to prevent the tip electrode from detaching, and in the eventof detachment, to tether the tip electrode to the catheter. A distal endof the safety wire is anchored in the tip electrode in blind hole 119(FIG. 8) and a proximal end is anchored at a location of the cathetershaft proximal of the portion of the catheter that enters the patient'sbody. The safety wire can be a Monell wire wrapped with copper.

As understood by one of ordinary skill in the art, distal end of thelead wire 40 for the tip electrode 37 is anchored (e.g., by soldering)in a blind hole 115 (FIG. 7 a) in a proximal face of the tip electrode.Distal ends of thermocouple wires 41 and 45 are likewise anchored in ablind hole 117 (FIG. 7 a) in the proximal face. The lead wire 40 for thering electrode is soldered at its distal end to an inner surface of thering electrode (FIG. 8) through a hole formed in the tubing 57. Thesolder location is aligned with the inclined channel 71 of the distalmagnetic member 38 a so that the lead wire 40 join the other componentssuch as the tip electrode lead wire 40, the thermocouple wires 41 and45, the injection needle 46, the safety wire 113 passing through theouter channel 49 of the mid-member 38 b toward the intermediate section14 (see FIG. 7).

In the illustrated embodiment, a distal transitional section 120 extendsbetween the tip section 36 and the intermediate section 14. As shown inFIGS. 8 and 9, the section 120 comprises short segments 121 of very softand flexible tubing in between which are positioned additional magneticdevices 124. In the disclosed embodiment, the section 120 is without astiffening tube, braiding or any other reinforcing structure. As such,the section 120 is floppy and considerably softer and more flexible thanthe intermediate section 14. The tubing can be PEBAX tubing withdurometer ranging between about 25D and 55D, preferably about 25D and35D, and more preferably about 25D. And, as illustrated in FIG. 9, thereare two additional magnetic devices 124 a and 124 b, each beinggenerally cylindrical with an inner passage through which the componentscan extend. To secure and protect the additional magnet devices, eachhas a heat shrink magnetic sleeve tubing 130. Like the magnetic device38, the additional magnets 124 are responsive to the MSS and providedadditional control for deflecting and positioning the tip section 36.Components including the lead wires, the thermocouple wires 41 and 45,the safety wire 113, and the electromagnetic sensor cable extend throughthe hollow interior of the transitional section 120.

The catheter 10 described above provides advantageous features,including a tip section 36 with an integrated position sensor 34 andmagnetic device 38 housed at a location optimally near the tip electrode37. As understood by one of ordinary skill in the art, space is at apremium in a catheter tip section and the tip section of the presentinvention efficiently integrates the solid position sensor and themodular magnetic device such that the tip section can accommodate theneeded predetermined volume of the magnetic device for proper responseto the MSS while still carrying the position sensor at a predetermineddistance from the distal end of the tip electrode.

FIGS. 10-13 illustrate another embodiment of a magnetically maneuverabletip section 36′ for ablation and injection, in accordance with thepresent invention. The tip section 36′ has structures similar to the tipsection 36 described above but both a position sensor 34′ and a magneticdevice 38′ have a hollow design to provide a generally linear passage119 for the components extending through the tip section, such as theinjection needle 46, the lead wire 40 for the tip electrode, the safetywire 113, and the thermocouple wires 41 and 45. In particular, theinjection needle 46 can travel a generally linear path 119 with reducedstress and friction during extension and retraction. A linear path oftravel is therefore preferred in certain instances, including wherecomponents in the tip section are fragile and susceptible to breakagedue to compressive and/or shear forces exerted by the components. Inparticular, components that extend and retract, such as an injectionneedle, can rub, break or wear down surfaces and structures itrepeatedly comes in contact with.

As illustrated in FIG. 12. the position sensor 34′ has a generallycylindrical body 131 that is hollow with an inner passage 132. Like thesensor 34, the sensor 34′ is adapted to detect location and orientationfor generating coordinate and angular data, (for example, x, y, pitch,roll, yaw). Position sensors of similar hollow designs are disclosed inU.S. Pat. No. 6,484,118, the entire disclosure of which is herebyincorporated by reference.

The magnetic device 38′ of FIG. 11 also has a generally cylindrical body140 that is hollow with an inner passage 142. Its outer diameter issized so that it can sit in the inner passage 132 of the position sensor34′ and when so stacked and assembled, the magnetic device 38′ and theposition sensor 34′ are in a surrounding and circumferentialrelationship and their respective inner passages 132 and 142 are axiallyaligned. Components extending between the tip electrode and theintermediate section pass through these inner passages. In particular,concentric inner passages 132 and 142 are on axis with the tip electrode37 and therefore axially-aligned with the needle duct 62 that definesthe concentric needle port 67, as shown in FIG. 13. As such, theinjection needle 46 travels a generally linear, on-axis path 111′ withminimal stress and friction during extension and retraction. In theillustrated embodiment, the injection needle travels the entire lengthof path 111′ in the tip section.

To ensure that the distal end of the sensor 34 is at the predetermineddistance L from the distal end of the tip electrode and that the tipsection 36 carries the predetermined volume of magnetic material, themagnetic device includes a magnetic spacer 38 d that slides into thedistal end of the magnetic device 38′. The spacer has a predeterminedlength T′ such that when its distal end is flush with the distal end ofthe magnetic device 38′, the proximal end of the spacer 38 d functionsas a stop against which the distal end of the sensor abuts for theproper distance L to the distal end of the tip electrode (see FIG. 13).The spacer also has an inner passage 142′ so that components can extendthrough it.

As illustrated in FIG. 11, the magnetic device can be formed with anintegrated spacer as a monolithic piece 38″ where a smaller drill bitforms a smaller inner passage 143 in the distal portion and a largerdrill bit forms a larger inner passage 144 in the proximal portion suchthat a stop 151 is formed at the junction of the smaller and largerinner passages.

The lead wire 40 for the tip electrode, the safety wire 113, and theinjection needle 46 each travel along the linear path 111′ through thehollow position sensor 34′ and the hollow magnetic device 38′ with theexception of the lead wire 40 for the ring electrode 54 which travelsalong an outer channel 49′ formed along the length of the magneticdevice 38′ and 38″. The channel may be formed by electrical dischargemachining (EDM) or any other suitable process.

In the illustrated embodiment of FIGS. 10-13, the hollow position sensorand magnetic device are in a surrounding or circumferential relationshipwith the position sensor in the interior of the magnetic device. It isunderstood by one of ordinary skill in the art that the position canalso be reversed, with the magnetic device being on the interior of theposition sensor. Since both have hollow configurations, either one canbe stacked on or slid over the other depending on their diameter. Atransitional section 120 with additional magnetic devices can also beconnected to the tip section 36′.

The preceding description has been presented with reference to presentlypreferred embodiments of the invention. Workers skilled in the art andtechnology to which this invention pertains will appreciate thatalterations and changes in the described structure may be practicedwithout meaningfully departing from the principal, spirit and scope ofthis invention. For example, the members and components may be sizeddifferent in that the drawings are not necessarily to scale. Also,components extending through the catheter may have an overtubing orsheath for insulation and/or protection. The magnetic device and theposition sensor may be configured differently but nevertheless beintegrated with each other in the tip section. Moreover, the cathetercan be adapted for irrigation to cool tissue during ablation. Thecatheter can also be structured without any control handle wheremanipulation and control of the catheter and extension, retraction andinjection of the needle are automated and/or accomplished remotely.

It is also understood that while the catheter of the present inventionis described with ablation, mapping and injection capabilities, ablationneed not be included. For example, an injection catheter having anelectromagnetic sensor and electrophysiology mapping electrodes may beused in combination with a separate ablation catheter system.

Accordingly, the foregoing description should not be read as pertainingonly to the precise structures described and illustrated in theaccompanying drawings, but rather should be read consistent with and assupport to the following claims which are to have their fullest and fairscope.

What is claimed is:
 1. A catheter comprising: a catheter body; anintermediate section distal of the catheter body; a tip section distalof the intermediate section, the tip section having a tip electrode withan omnidirectional distal tip and a concentric needle port, the tipsection also having a magnetic device and a position sensor, with atleast portions of each of the magnetic device and the position sensorbeing in a surrounding relationship with each other in the tip section;a needle extending through the catheter body, the intermediate sectionand the tip section; and a needle control handle adapted to extend andretract the injection needle through the concentric needle port.
 2. Acatheter of claim 1, wherein the magnetic device includes a hollowmember in which the sensor is positioned.
 3. A catheter of claim 1,wherein the magnetic device and the position sensor have an integratedconfiguration.
 4. A catheter of claim 1, wherein the integratedconfiguration is adapted with a path for at least one component to passbetween the tip electrode and the intermediate section.
 5. A catheter ofclaim 4, wherein the path is generally linear.
 6. A catheter of claim 4,wherein the path is nonlinear.
 7. A catheter of claim 5, wherein thepath is in communication with and generally aligned with the concentricneedle port.
 8. A catheter of claim 6, wherein the path is incommunication with the concentric needle port.
 9. A catheter of claim 4,wherein the component is the needle.
 10. A catheter of claim 4, whereinthe component is a lead wire, thermocouple wire, electromagnetic sensorcable, irrigation tube or tip electrode safety wire.
 11. A catheter ofclaim 9, wherein the injection needle is made of nitinol.
 12. A cathetercomprising: a catheter body; an intermediate section distal of thecatheter body; a tip section distal of the intermediate section, the tipsection having a tip electrode with an omnidirectional distal end and aconcentric needle port, the tip section also having an integratedmagnetic device and position sensor wherein at least one of the magneticdevice and position sensor has a hollow configuration to receive atleast a portion of the other.
 13. A catheter of claim 12, wherein themagnetic device includes a distal member, a main hollow member and aproximal member, the position sensor being situated in the main hollowmember with a distal end of the position sensor abutting a proximal endof the distal member.